# Grades & Study Calc

Grade needed on a final, weighted grades, GPA, percent to letter, curves, percentile rank, reading plans and study time.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://grades-calc.x402tookit.com/openapi.json
- x402 manifest: https://grades-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://grades-calc.x402tookit.com/catalog
- Health (free): https://grades-calc.x402tookit.com/health
- Uptime (free): https://grades-calc.x402tookit.com/uptime

## Endpoints (8)

### GET /final-grade-needed — $0.02
Score needed on a final exam (or any remaining work) to reach a target class grade, from current grade and its weight.
Params: currentGrade: number, finalWeight: number, targetGrade: number
Example: https://grades-calc.x402tookit.com/final-grade-needed?currentGrade=85&finalWeight=30&targetGrade=80

### GET /gpa — $0.02
GPA on the 4.0 scale from letter grades and credits, with optional honors (+0.5) and AP/IB (+1.0) weighting.
Params: courses: string, weighted?: string
Example: https://grades-calc.x402tookit.com/gpa?courses=%5B%7B%22grade%22%3A%22A%22%2C%22credits%22%3A3%7D%2C%7B%22grade%22%3A%22B%2B%22%2C%22credits%22%3A4%7D%2C%7B%22grade%22%3A%22C%22%2C%22credits%22%3A3%7D%5D

### GET /grade-curve — $0.02
Curve test scores by adding points, scaling so the top score is 100, or the square-root method, with before and after averages.
Params: scores: string, method: string, points?: number, cap?: string
Example: https://grades-calc.x402tookit.com/grade-curve?scores=60%2C70%2C80%2C90&method=sqrt

### GET /percent-to-letter — $0.02
Letter grade and 4.0 GPA points for a percentage on the common US scale, with plus/minus, and points to the next grade.
Params: percent: number, plusMinus?: string, roundHalfUp?: string
Example: https://grades-calc.x402tookit.com/percent-to-letter?percent=92.9

### GET /percentile-rank — $0.02
Percentile rank of a score in a class list (mean-rank method), with rank from the top, mean, median and z-score.
Params: scores: string, yourScore: number
Example: https://grades-calc.x402tookit.com/percentile-rank?scores=50%2C60%2C70%2C80%2C90&yourScore=70

### GET /reading-planner — $0.02
Pages per day to finish a reading assignment by the due date, daily minutes at your pace, and a day-by-day page schedule.
Params: totalPages: integer, pagesAlreadyRead?: integer, days: integer, pagesPerHour?: number, restDays?: integer
Example: https://grades-calc.x402tookit.com/reading-planner?totalPages=300&days=12&pagesPerHour=40

### GET /study-time — $0.02
Weekly study hours from credit hours using the 2 to 3 hours per credit rule, with total weekly workload and a daily plan.
Params: creditHours: number, hoursPerCredit?: number, classDaysStudied?: integer, jobHoursPerWeek?: number
Example: https://grades-calc.x402tookit.com/study-time?creditHours=15&hoursPerCredit=2&classDaysStudied=5

### GET /weighted-grade — $0.02
Overall class grade from categories or assignments with scores, maximums and weights, normalizing weights that do not total 100.
Params: items: string
Example: https://grades-calc.x402tookit.com/weighted-grade?items=%5B%7B%22name%22%3A%22Homework%22%2C%22score%22%3A90%2C%22max%22%3A100%2C%22weight%22%3A40%7D%2C%7B%22name%22%3A%22Exams%22%2C%22score%22%3A80%2C%22max%22%3A100%2C%22weight%22%3A60%7D%5D

## Terms

Grade arithmetic computed locally from the numbers given, using common US conventions (10-point letter scale, 4.0 GPA scale), provided as is. Schools and teachers differ in scales, weights, rounding, plus/minus grades and honors weighting, so always check your syllabus and your school's published policy. Not an official transcript or an academic decision.